Advanced Exergetic Analysis of a Double-Effect Series Flow Absorption Refrigeration System

This paper contains theoretical results of an advanced exergy study of a double-effect series flow absorption refrigeration cycle. Traditional second law of thermodynamics analysis was performed and revealed the absorber as the component with the highest exergy destruction of the system. In the evaporator, ≈49.34% of the exergy destruction is avoidable and almost in it’s entirety, ≈99.12% is of endogenous nature. The highest potential for improvement of the high-pressure generator is its design and manufacture because ≈67.47% of the endogenous exergy destruction is avoidable. A parametric study was presented to discuss the sensitivity of splitting exergy destruction concepts taking into account temperature variations in the absorber and condenser temperatures and the heat source temperature.

A single-pieced, fully air-driven, cuff-inserted pseudo-blood pressure generator for on-site pre-screening test of non-invasive blood pressure monitor by nurses

Background It is crucial to frequently inspect the proper operation of non-invasive electronic blood pressure monitors in various sites to prevent accidents from inaccurate blood pressure measurements, especially for large-scale hospitals. However, most conventional blood pressure monitor inspection devices are not suitable for such on-site investigation purpose. In this study, we propose a new single-pieced, fully air-driven pseudo blood pressure generator that is suitable for frequent on-site pre-screening tests of the blood pressure monitor by nurses. Results The proposed model comprises a rigid cylindrical body, two simulated brachial arteries, two air-pumps, an electronic controller, and a pressure sensor. Control algorithm based on polynomial curve fitting was implemented to generate various user-instructed systolic blood pressure and heart-rate conditions automatically. To evaluate the performance and clinical feasibility of the proposed model, various experiments were performed using ten commercial electronic blood pressure monitors. Experimental results demonstrated that the values of the Pearson coefficient between the reference pseudo-blood pressure waveforms and the actually generated pressure waveforms were 0.983, 0.983 and 0.997 at 60, 70 and 80 beats/min, respectively (p < 0.05). Besides, during the experiments using ten commercial blood pressure monitors, the maximum error in average systolic blood pressure was 2.9 mmHg, the maximum standard deviation in average systolic blood pressure was 3.5 mmHg, and the maximum percentage error in average pumping rate was 3.2%, respectively. Conclusions We expect that the proposed model can give an easy and comprehensive way for frequent on-site investigations of the blood pressure monitors by nurses, and improve the safety of patients with abnormal blood pressure, especially in most large-scale hospitals.

Research on the low-frequency pressure generator based on magnetic fluid

To solve the problems that the existing pressure generators require high mechanical excitation frequency, need large manufacturing cost and are hard to control, a kind of pressure generator with low-frequency based on magnetic fluid is proposed in this paper. Magnetic fluid possesses the advantages of both magnetism of solid magnetic material and fluidity of liquid. The first-order buoyancy of magnetic fluid changes with low frequency alternating magnetic field. Based on this, the superimposed magnetic field is generated by electrifying the conical solenoid coil connected with the long solenoid coil with magnetic core in parallel. Magnetic field and magnetic force in the model are analyzed, then the relationship between input current and output pressure is calculated. In addition, the experimental platform is built and the performance of the device is tested. The result shows that the pressure generator can produce the corresponding pressure signal according to the input current.